please fallow the documents to fix your problem. you 1st need to setup an Dev account for ios and android. this issue you are having is you have not setup your provision profile or your signing key. but to get those you need to fallow the docs bellow. hope this helps you.
for IOS.
then do this.
https://docs.unrealengine.com/latest/INT/Platforms/iOS/QuickStart/3/index.html
For Android.
go to.
search on answers how to set up android.